« Respuesta #24 en: Miércoles 28 Febrero 2024 11:52:32 am »
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https://www.researchgate.net/publication/372889143_Long-term_surface_impact_of_Hunga_Tonga-Hunga_Ha'apai-like_stratospheric_water_vapor_injection
Abstract
The amount of water vapor injected into the stratosphere after the eruption of Hunga Tonga-Hunga Ha’apai (HTHH) was unprecedented, and it is therefore unclear what it might mean for surface climate. We use climate model simulations to assess the long-term surface impacts of stratospheric water vapor (SWV) anomalies caused by volcanic eruptions. The simulations show that the SWV anomalies lead to strong and persistent warming of Northern Hemisphere landmasses in boreal winter, and austral winter cooling over Australia. Thus, SWV forcing from volcanic eruptions like the one from Hunga Tonga-Hunga Ha’apai can have surface impacts on a decadal timescale. We also emphasize that the surface response to SWV anomalies is more complex than simple warming due to greenhouse forcing and is influenced by factors such as regional circulation patterns and cloud feedbacks. Further research is needed to fully understand the multi-year effects of SWV anomalies and their relationship with climate phenomena like El Niño Southern Oscillation.
Análisis y modelización
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Despite using a full chemistry-climate model, this is still an idealized experiment and there are significant limitations on the interpretation of the response predicted here, particularly around the use of a climatological SST. However, we focus on surface impact over land masses, andthe anomalous atmospheric circulations which are responsible for those signals over land. We also chose to favor alarge number of ensemble members and longer simulationsover a fully coupled ocean, as that addition would severely limit our capacity in terms of ensemble size and simulation length.
2) MiMA
To alleviate some of the restrictions on atmosphere ocean interactions, we run additional ensemble simulations with the Model of an idealized Moist Atmosphere (MiMA, Jucker and Gerber 2017), an intermediate-complexity moist general circulation model. The advantage of this model is that it includes a mixed layer ocean, allowing for an estimate of how SSTs might be influenced by the SWV and ozone perturbations produced in WACCM.
MiMA is based on GFDL AM2.1 atmospheric model with a spectral dynamical core, which we run at T42 resolution ( 2.8 degrees) and 40 vertical levels up to 0.07 hPa.
MiMA includes interactive water vapor including evaporation and condensation, and a simplified convection scheme following Frierson et al. (2007), but it does not include any representation of cloud physics. Full radiative transfer is computed with the Rapid Radiative Transfer Model RRTMG (Mlawer et al. 1997), but here we fix ozone and water vapor to the monthly values from our WACCM simulations (monthly means linearly interpolated to each radiation time step). We include a homogeneous CO2 concentration of 390 ppm, the solar constant is set to 1370 Wm−2, and surface albedo follows Garfinkel et al. (2020b) with a value of 0.23 at low latitudes and 0.80 in polar regions.
We run MiMA in a configuration following the Southern Hemisphere benchmark case of Garfinkel et al. (2020a), which most notably includes a gravity wave scheme and surface ocean heat fluxes mimicking the major ocean currents plus a realistic Intertropical Convergence Zone (ITCZ) and South Pacific Convergence Zone (SPCZ)
(Fig. B1). Land surface includes realistic topography, increased surface roughness, restricted evaporation, higher albedo (0.43) for the major deserts, and lower heat capacity (10 million Jm−2K−1 vs. 100-300 million Jm−2K−1 for
water).
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